Folding chair

ABSTRACT

Disclosed is a folding chair comprising a frame and a seat sheet, which has means for protecting a user&#39;s vertebral column and means for expanding the seat to improve its seating comfort and stability. The expanding means are connected to both sides of the seat, and the protecting means is coupled at its opposite ends to armrests, upper portions of frame elements or the expanding means. The expanding means are hanged on projections formed by bending upper portions of the front frame elements. The protecting means is held at a certain height on a back rest of the chair but being allowed to be laterally moved by holding means, thereby enabling length of the protecting means to be adjusted. The folding chair may have one or more means for protecting a user&#39;s vertebral column.

TECHNICAL FIELD

The present invention relates, in general, to a folding chair and, moreparticularly, to a folding chair intended to be diversified in itsapplication and convenient for seating, which is provided with means forprotecting a user's vertebral column and means for expanding and stablysupporting a seat portion, whereby the folding chair can affordcomfortable and stable seating feeling and protection for vertebralcolumn to a user and can prevent various afflictions caused by unstableseating posture of a user.

BACKGROUND ART

As well known to those skilled in the art, a usual conventional foldingchair is constructed in such a way that frame elements constitutingframe legs are crossed with one another to form a frame of apredetermined shape and then a seat sheet of a desired shape is held onthe frame by means of appropriate joint means. Alternatively, aconventional folding chair may be constructed in such a way that a frameis prepared by providing support frame elements mounted on rear basemembers with slide members slidably inserted thereon, connecting sideframe elements constituting side frame legs between the base members andupper connecting members and between the slider members and lowerconnecting members to form an “X” shape, and connecting front frameelements constituting front frame legs between the upper and lowerconnecting members to form an “X” shape, and then a fabric seat sheet isheld on the frame.

However, the above-mentioned conventional folding chair is no more thana simple folding chair in its application, and thus cannot afforddiverse uses and seating comfort and stability to a user.

Such a conventional folding chair is merely intended to ensure ease ofits carriage and storage, and is well known to those skilled in the art.

Furthermore, various improvements of the above folding chair have beenproposed by the applicant and have been put to practical use. Also, theabove folding chairs are equipped with various functions to improveconvenience of its manipulation, and they are previously in applied,pending or patented status.

More specifically, the above mentioned folding chairs and theapplicant's folding chairs allow carriage in folded state, ease ofstorage and convenient use in unfolded state. Furthermore, the foldingchairs are equipped with various functions such as attachment of a footrest and storage of miscellaneous articles to further improve a user'sconvenience.

However, the improvements of the folding chairs are no more than slightincrease in their convenience and applications, and they cannot affordseating comfort and stability and protection for a user's vertebralcolumn in use.

In other words, because the folding chairs are constructed by fixedlycoupling corner portions of seat sheets to front frame legs and rearframe legs, a user's buttock and vertebral column portions arepositioned at the center of the seat sheet, thereby causing the centerportion of the seat sheet to droop and thus the user's buttocks arepositioned between the plane defined by the fixed corners and the groundsurface. As a result, even when the user moves slightly, the foldingchairs is easily shaken or falls down.

Since such an unstable seating posture may give the user unreasonablediscomfort, patients suffering disease cause by abnormal disk and weakvertebral column cannot use the folding chairs. In addition, even a userwith a healthy body is liable to suffer backache when he or she sits inthe chair for a long time.

The above problems are brought about by the fact that a seat sheetcannot be rigidly secured to the frame element, and a profile definedbetween a neck portion and a buttock of a user assumes an arched shape,thereby giving his of her vertebral column unreasonable load when theuser sits in the folding chair. Consequently, occurrence of backache isinevitable after long hours of seating, such as while fishing andreading.

Furthermore, since two front corners of a seat sheet are coupled to andsupported by front frame legs and two rear corners are coupled to andsupported by rear frame legs, a user's body weight is concentrated onthe center of a seat sheet, thereby causing a user's buttock portion tobe positioned under his knees to have abnormal posture.

In such a posture, because the two front corners of the seat sheet aresupported by the front frame legs, a supporting line is generated at afront side of the seat sheet. Therefore, the supporting line thushinders smooth blood circulation of femoral area, thereby causing legsand feet to be numbed after long hours of seating.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide a folding chair which is provided with means forprotecting a user's vertebral column and means for expanding a seatsheet so as to give a user seating comfort and stability, and preventionof various afflictions caused by unstable body posture.

Another object of the present invention is to apply the means forprotecting a user's vertebral column and the means for expanding a seatsheet to many of types of folding chairs.

A further object of the present invention is to provide a folding chairwhich is provided at its back rest with detachable holding means forallowing the means for protecting a user's vertebral column to bedisposed at a desired position.

A further object of the present invention is to provide a folding chairwhich is provided at its back rest with a plurality of bands, eachhaving upper and lower ends attached thereto, to allow the means forprotecting a user's vertebral column to be laterally moved therein whilebeing maintained in position, so that the means is positioned at apredetermined position.

A further object of the present invention is to provide a folding chairwhich is provided at its back rest with means for protecting a user'svertebral column, which can be releasably attached thereto, coupled atits opposite ends to arm rests and adjusted in its length in accordancewith a user's body type.

In order to accomplish the above object, the present invention providesa folding chair including a frame constructed by a plurality of frameelements, and a seat unit held on the frame by means of holding meansand having a seat portion and a back rest portion which are integrallyformed, comprising: means for outwardly expanding the seat portion ofthe seat unit, which are connected to both sides of the seat portion,and means for protecting a user's vertebral column by supporting theback rest portion, which is coupled at its opposite ends to arm restsheld on upper portions of front frame elements.

The means for protecting a user's vertebral column may be held on a backrest of the chair by holding means which allows the protecting means tobe moved. The means for protecting a user's vertebral column may becoupled to arm rests, frame elements or the expanding means. One or moremeans for protecting a user's vertebral column may be provided in thefolding chair, as required.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a perspective view showing a folding chair according to themost preferable embodiment of the present invention;

FIGS. 2 to 5 are perspective views showing expanding means andassociated components of the invention;

FIG. 6 is a perspective view showing a folding chair to which onlyexpanding means of the invention is applied;

FIG. 7 is a perspective view showing a folding chair of a secondembodiment of the invention having means for protecting a user'svertebral column;

FIGS. 8 and 9 are perspective view showing folding chairs which areprovided with only protecting means of the invention;

FIG. 10 is a side elevation view showing a protecting means of theinvention in use;

FIG. 11 is a rear view of a folding chair having another embodiment ofprotecting means according to the invention;

FIGS. 12 to 14 are rear views of a folding chair having furtherembodiments of protecting means according to the invention;

FIG. 15 is a perspective view showing a way for coupling ends ofprotecting means of the invention to frame elements;

FIG. 16 is a view similar to FIG. 15, but showing another way forcoupling ends of protecting means of the invention to frame elements;

FIG. 17 is a view similar to FIG. 15, but showing a further way forcoupling ends of protecting means of the invention to frame elements;

FIG. 18 is a view similar to FIG. 15, but showing a further way forcoupling ends of protecting means of the invention to arm rests;

FIG. 19 is a view similar to FIG. 15, but showing a further way forcoupling ends of protecting means of the invention to arm rests;

FIG. 20 is a perspective view showing another type of folding chairhaving means for protecting a user's vertebral column of the invention;

FIGS. 21 to 23 are perspective views showing further types of foldingchairs having the protecting means of the invention; and

FIGS. 24 and 25 are perspective views showing two-person andthree-person folding chairs to which the protecting means of theinvention are applied.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference now should be made to the drawings, in which the samereference numerals are used throughout the different drawings todesignate the same or similar components.

FIGS. 1 to 19 show folding chairs according to embodiments of thepresent invention. As shown in the drawings, the folding chair of theinvention comprises a frame 1 constructed by a plurality of frameelements 11, and a seat unit 2 held on the frame 1 by means of usualholding means and having a seat portion 21 and a back rest portion 22which are integrally formed.

The seat portion 21 of the seat unit 2 is provided at its opposite sideswith longitudinal expanding pockets 4. Vertebral column-protecting meansis provided under the back rest portion 22, which is supported by armrests 23 provided at both sides of the frame 1.

Each of the longitudinal expanding pockets 4 is made of fabric andoutwardly extended from the seat portion 21 of the seat unit 2 to have apredetermined width, and stitched along its peripheral edge with a frontend being opened to have an insertion hole 21 a therein, as illustratedin FIG. 2.

A support hanger 11 a of a predetermined length is inserted into each ofthe insertion holes 21 a, which is formed by bending an upper end ofeach of the front crossed frame legs 11, so that the seat portion 21 canbe expanded by outward motion of the support hangers 11 a.

The expanding pockets 4 downwardly pushes the seat portion 21 by auser's body weight, and the body weight is transmitted to supporthangers 11 a of the front crossed frame legs 11 to further expand theseat portion 21, when a user sits down on the seat portion 21.

Consequently, compressed areas of femora of a user, on which body weightof the user is concentrated, are enlarged. With such enlargement ofcompressing areas of femora, the user can comfortably rest withoutobstruction of blood circulation, even in case of long hours of seating.

The support hangers 11 a of the front crossed flame legs 11 areconstructed such that upper ends of the crossed frame legs 11 arerearwardly bent to have predetermined lengths and then arm rest hangers11 b intended for supporting the arm rests 23 are separately attached tobent portions of the crossed frame legs, as shown in FIGS. 2 and 3.

Alternatively, the support hangers 11 a may be constructed such thatupper portions of the crossed frame legs 11 are rearwardly bent bypredetermined lengths and then forwardly bent, and the upper endsthereof are outwardly bent to form the arm rest hangers 11 b, as shownin FIGS. 4 and 5.

In the embodiment shown in FIG. 3, the seat unit 2 is provided at itsfront side with extending straps 21 b, each of which is stitched at itsopposite ends the seat unit to form a ring. The pair of crossed framelegs 11 are provided with slide pads 11 c, respectively, which areslidably inserted over the upper sections of the crossed frame elements11. Each of the slide pads 11 c is provided at its side with a pair ofprotrusions, at each of which is formed a pin hole 11 d to be insertedwith a pin 11 e. Therefore, the extending straps 21 b can be preferablyconnected to the slide pads 11 c by inserting the pins 11 e into theholes of the extending straps 21 b through the pin holes 11 d of theslide pads 21 b.

FIG. 6 shows another embodiment of a folding chair according to thepresent invention, which has longitudinal expanding pockets 4. Thefolding chair shown in the drawing is designed for cases where it isunnecessary to have arm rests. In this case, the front crossed framelegs 11 are rearwardly bent at upper ends thereof to form supporthangers 11 a each having a predetermined length. The support hangers 11a are inserted into the holes 21 a of the expanding pockets 4 to tightlysupport the seat unit 2.

FIG. 7 shows a further embodiment of a folding chair according to thepresent invention. In this embodiment, a vertebral column-protectingmeans 3 is connected at its opposite ends to the longitudinal expandingpockets 4 or ends of the support hangers 11 a of the front crossed framelegs 11.

The vertebral column-protecting means as mentioned above will now bedescribed in detail.

Although it is preferable that the vertebral column-protecting means 3is coupled at its opposite ends to the arm rest 23 held on the frontcrossed frame legs 11 by stitching, the vertebral column-protectingmeans 3 may be directly coupled to upper ends of the front crossed framelegs 11, if required.

Furthermore, although it is preferable that the vertebralcolumn-protecting means 3 comprises only one band having predeterminedlength and width, the vertebral column-protecting means 3 may bereleasably provided at its middle portion with an additional enlargedsupporting member 31, as illustrated in FIG. 9.

In this case, the enlarged supporting member 31 is preferably enlargedtoward its middle portion to form an approximately elliptical shape, andis attached to the vertebral column-protecting means 3 by stitching.

Alternatively, the vertebral column-protecting means 3 may be providedat its middle portion with an additional enlarged rectangular member31′, as illustrated in FIGS. 11 to 13. In this case, the rectangularmember 31′ is provided with slits 31 a so that the band-shaped vertebralcolumn-protecting means 3 can pass therethrough while alternately goingalong its front surface and rear surface. Therefore, the rectangularsupporting member 31′ can be moved from side to side by a user.

The band material constituting the vertebral column-protecting means 3is positioned to be contact with a back surface of the back rest portion22 of the seat unit 2.

In an embodiment shown in FIG. 14, a back surface of the back restportion 22 is provided at its both sides with a pair of holding bands 5a, each of which is of a predetermined length and is verticallypositioned. Each of the holding bands 5 is stitched at its upper andlower ends to the back rest portion 22 to define a passage between theupper and lower ends. The vertebral column-protecting means 3 passesthrough the passages of the pair of holding bands 5 a so that thevertebral column-protecting means 3 cannot be separated from the backrest portion. Therefore, when a user sits in the folding chair, i.e. theseat unit 21, the back rest portion 22 will be positioned at thevertebral column portion of the user by the vertebral column-protectingmeans 3 so that the vertebral column-protecting means 3 can comfortablysupport the vertebral column of the user.

In embodiments shown in FIGS. 11 to 13, a back surface of the back restportion 22 of the seat unit 2 is provided at its lower portion with oneor more Velcro fasteners 5 each having a predetermined surface area. Theenlarged supporting member 31, 31′ is also provided at its inner surfacewith the mating Velcro fasteners to be detachably attached to the Velcrofastener 5 of the back rest portion 22. Consequently, a user can easilyadjust height of the vertebral column-protecting member 3 and theenlarged supporting member 31, 31′ by means of the Velcro fasteners inaccordance with his body type.

The reason why the vertebral column-protecting means can efficientlyfulfill its protecting role is that the vertebral column-protectingmeans 3 is coupled at its opposite ends to the arm rests 23 or upperends of the frame legs 11 adapted to support the arm rests 23 so thatthe vertebral column-protecting means 3 inhibits the back rest portions23 from drooping or from being expanded.

To this end, the opposite ends of the vertebral column-protecting means3 is coupled to the arm rests 23 by using stitching or usual couplingmeans, and the vertebral column-protecting means 3 is provided with alength adjusting means 6 which enables a length of the vertebralcolumn-protecting means 3 to be easily adjusted in accordance withuser's body type.

The vertebral column-protecting band means 3 may be provided at itsopposite ends with separate eyelets 7 so that the eyelets 7 can be slidalong the crossed frame elements 11 during assembly of the foldingchair, as illustrated in FIG. 15.

Alternatively, the opposite ends of the vertebral column-protectingmeans 3 may be folded and then stitched so as to form ring-shaped straps71, as illustrated in FIG. 16. With the ring-shaped straps 71, the endsof the vertebral column-protecting means 3 can be also slid along thecrossed frame elements 11.

FIGS. 18 and 19 show means for connecting ends of the vertebralcolumn-protecting means 3 to the arm rests 23.

In an embodiment shown in FIG. 18, the vertebral column-protecting means3 is provided at its opposite ends with hooks 72, and the arm rests areprovided with a plurality of eyelets 8. Therefore, a user can adjustlength of the vertebral column-protecting means 3 in accordance with hisbody type by coupling the hook 72 to a corresponding one of the eyelets8.

Alternatively, an embodiment shown in FIG. 19 includes a plurality ofrings 81 attached to the lower surface of the arm rest 23 so as to causethe hook 72 to be disposed under the arm rest 23. Therefore, thisembodiment is intended for alleviating or eliminating inconveniencecaused by the hooks 72 or the vertebral column-protecting means 3disposed on the arm rest 3 as well as adjusting the length of thevertebral column-protecting means in accordance with a user's body type.

FIG. 20 shows a folding chair adapted to be folded and unfolded inanother way, to which the principle of the present invention is alsoapplied.

As shown in the drawing, the folding chair includes the frame 1 composedof a plurality of bent frame elements 11 and the seat unit 2 composed ofthe seat portion 21 and the back rest portion 22. A plurality of tensionsprings are connected to a back surface of a linear bent portionpositioned at a boundary between the back rest portion 22 and the seatportion 21 of the seat unit 2 so that body weight of a user can besupported by the tension springs when being sat by the user.

Such a chair may encounter the problems as mentioned in the introductionof the specification. As is the case with the above-mentionedembodiments, the folding chair is provided the vertebralcolumn-protecting means 3 such that the vertebral column-protectingmeans 3 is positioned at a lower portion of the back rest portion 22.The vertebral column-protecting means 3 may be held on the back restportion 22 by attaching additional holding bands, Velcro fastener oranother holding means, and may be fixed at its opposite ends to armrests or front frame elements by appropriate fixing means.

FIGS. 21 to 23 show other folding chairs to which the vertebralcolumn-protecting means 3 of the invention is applied. That is, FIG. 21shows a folding chair having a foot rest assembly which is releasablyinstalled thereto, FIG. 22 shows a folding chair having a frame which iscomposed in another way, and FIG. 23 shows a folding chair which isprovided with a tilting apparatus for the back rest portion, and cupholders 9 disposed at front portions of the arm rest 23.

The vertebral column-protecting means, which are applied to the foldingchairs illustrated in the drawings, are also fixedly or releasablycoupled at its opposite ends to the arm rests 23, as is the case withthe above embodiments. Furthermore, the folding chairs are provided attheir back rest portion with the holding means for holding the vertebralcolumn-protecting bands, which are also fixedly or detachably attachedto the back surface of the back rest portion.

In the embodiments shown in FIGS. 8 to 23, although there are shown onlythe vertebral column-protecting means, the folding chairs according tothe embodiments may of course have the expanding pockets 4. Theexpanding pockets 4 may be embodied into various modifications dependingon the type or the folding way of the chairs.

FIGS. 24 and 25 show commonly used two-person and three-person foldingchairs which are also provided with the vertebral column-protectingmeans 3 of the present invention so as to provide a user with the senseof comfort and stability and to protect user's vertebral column.

In the embodiments shown in the drawings, the two-person andthree-person folding chairs have two and three vertebralcolumn-protecting bands 3, respectively, which are coupled at theiropposite ends to upper ends of the front crossed frame elements 11 anddisposed at a lower portion of a rear surface of a back rest portion 22.

The vertebral column-protecting bands 3 are adapted to pass throughslots 22 a formed at a lower portion of the back rest portion 22 so thatthe vertebral column-protecting bands 3 can individually move throughthe slots 22 a.

Of course, the folding chairs of these embodiments may have means foradjusting lengths of the vertebral column-protecting bands, means forholding the bands in the back rest portion, and additional componentssuch as foot rests and cup holders in the same way as those of the aboveembodiments.

INDUSTRIAL APPLICABILITY

As described above, the present invention provides a folding chairhaving vertebral column-protecting means and means for expanding itsseat unit so that a user can feel comfort and stability and can beprotected from injury to his vertebral column. Consequently, the foldingchair of the present invention can protect a user from various diseasescaused by unstable seating posture and can multiply comfort andstability. Since the vertebral column-protecting band can beappropriately applied to many kinds of chairs depending on structuresand use of chairs, its range of application become considerably wide,Furthermore, since the vertebral column-protecting band can be held inthe back rest portion by means of holding bands, or it can be attachedto the back rest portion by means of attaching means such as Velcrofastener so that position of portion of the back rest portion which issupported thereby can be conveniently varied.

Although the preferred embodiments of the present invention have beendescribed with reference to specific folding chairs, it should beunderstood that the invention is not limited to the illustrated specificembodiments but can be also applied to various chairs composed of frameelements joined by joint means. In addition, since a vertebralcolumn-protecting band of the invention can be appropriately applied tovarious folding chairs in accordance with their configuration and use,the invention can be applied to any chairs based on folding mechanism.Those skilled in the art will appreciate that various modifications,additions and substitutions are possible, without departing from thescope and spirit of the invention as disclosed in the accompanyingclaims.

1. A folding chair including a frame constructed by a plurality of frameelements including front frame elements, and a seat unit held on theframe by means of holding means and having a seat portion and a backrest portion which are integrally formed, comprising: means connected toboth sides of the seat portion for outwardly expanding the seat portion;a pair of arm rests held on upper portions of the front frame elements,with an arm rest on each of two opposite sides of said chair; and meanscoupled at its opposite ends to the arm rests for protecting a user'svertebral column by supporting the back rest portion.
 2. A folding chairincluding a frame constructed by a plurality of frame elements, and aseat unit held on the frame by means of holding means and having a seatportion and a back rest portion which are integrally formed, comprising:means connected to both sides of the seat portion for outwardlyexpanding the seat portion; a pair of arm rests held on upper portionsof front frame elements, with an arm rest on each of two opposite sidesof said chair; and means coupled at its opposite ends to the arm restsfor protecting a user's vertebral column by supporting the back restportion; wherein the expanding means is made by stitching portionsextended from both sides of the seat portion to form pockets ofpredetermined width each having a hole, and support hangers, which areformed by rearwardly bending upper ends of the front frame elements, areinserted in the holes of the pockets, whereby the seat portion can beexpanded by extending motions of support hangers of the frame elements.3. The folding chair as set forth in claim 2, wherein the upper ends ofthe frame elements are provided at their upper surfaces or lowersurfaces with additional arm rest hangers for supporting arm rests. 4.The folding chair as set forth in claim 2, wherein the frame elementsare rearwardly bent at their upper portion to form the support hangersand then outwardly bent at their upper ends to form the arm resthangers.
 5. The folding chair as set forth in claim 2 or 3, wherein theseat portion is provided at its front sides with extending straps eachhaving a hole, and the front frame elements are provided with slide padshaving holes into which the front frame elements are inserted and whichhave connecting pins adapted to be coupled to the extending straps. 6.The folding chair as set forth in claim 2 or 3, wherein the vertebralcolumn-protecting means is coupled to the expanding pockets or the upperbent ends of the front frame elements.
 7. The folding chair as set forthin claim 2, wherein the vertebral column-protecting means is coupled atits opposite ends to upper ends of the front frame elements by which thearm rests are supported.
 8. The folding chair as set forth in claim 2 or7, wherein the vertebral column-protecting means comprises a band bodyhaving a predetermined length and a predetermined width.
 9. The foldingchair as set forth in claim 8, wherein the band body is provided at itsmiddle portion with an additional enlarged supporting member fixedthereto, and the enlarged supporting member is increased in its widthtoward its middle portion to form an approximately elliptical shape. 10.The folding chair as set forth in claim 8, wherein the band body isprovided at its middle portion with an additional enlarged rectangularsupporting member adapted to slide therealong, and the rectangularsupporting member is formed with slits through which the band bodypasses, so that the rectangular supporting member is moved along theband body from side to side by a user.
 11. The folding chair as setforth in claim 8, wherein the band body constituting the vertebralcolumn-protecting means is disposed to be in contact with a rear surfaceof the back rest, and the rear surface of the back rest is verticallyprovided at its both sides with a pair of holding bands, each of theholding bands being stitched at its upper and lower ends to form apassage therebetween, so that the holding bands slidably confined in theholding bands are disposed at a user's vertebral column and stablysupport the user's vertebral column when the user sits down on the seatportion.
 12. The folding chair as set forth in claim 8, wherein the backrest portion is provided at a lower portion of its rear surface with oneof a hook or loop fastener fixedly attached thereto, and the band bodyis provided with a correspondingly mating loop or hook fastener, so thatthe band body is detachably attached to the back rest portion.
 13. Thefolding chair as set forth in claim 8, wherein the band body is providedat its opposite ends with eyelets which are inserted over the frontframe elements during assembly of the folding chair.
 14. The foldingchair as set forth in claim 8, wherein the band body is provided at itsopposite ends with ring-shaped straps which are made by stitching endsof the band and which are inserted over the front frame elements duringassembly of the folding chair.
 15. The folding chair as set forth inclaim 8, wherein the vertebral column-protecting means is provided atits opposite ends with hooks and the arm rest is provided with aplurality of eyelets so that the vertebral column-protecting means isadjusted in its length depending on body type of a user by connectingthe hooks of the vertebral column-protecting means to desired eyelets ofthe eyelets.
 16. The folding chair as set forth in claim 15, wherein thearm rest is longitudinally provided at its lower surface with aplurality of rings attached thereto, and the hooks of the vertebralcolumn-protecting means are coupled to the rings.
 17. The folding chairas set forth in claim 8, wherein the folding chair is adapted toaccommodate two or three persons, and thus the corresponding number ofvertebral column-protecting means are prepared therein and coupled attheir opposite ends to upper ends of the front frame elements, whereinthe vertebral column-protecting means pass through slots formed at theback rest portion such that the vertebral column-protecting means aredisposed at a lower portion of the back rest portion.
 18. The foldingchair as set forth in claim 2, wherein the vertebral column-protectingmeans is coupled at its opposite ends to the arm rest by stitching. 19.The folding chair as set forth in claim 2 or 7, wherein the vertebralcolumn-protecting means is provided with means for adjusting length ofthe vertebral column-protecting means to allow the vertebralcolumn-protecting means to be easily shortened or lengthened dependingon body type of a user.
 20. The folding chair as set forth in claim 2,wherein a plurality of tension springs are coupled to a corner portionof the seat unit corresponding to a boundary between the seat portionand the back rest portion so as to support body weight of a user whenthe user sits down on the seat unit.